The invention relates to a thread changing system for thread winding machines of the type in which a thread change mechanism is provided for positioning the threads relative to a package on which the threads are to be wound.
Winding machines with at least two winding mandrels are known, whereby one mandrel of which is held in a position of readiness, while the material is wound on at least one other mandrel. As soon as the package on the first mandrel is full, the second mandrel is moved from the position of readiness into a winding position whereby the material to be wound must be transferred from one package to the other. Such winding machines are well known. They normally contain a so-called revolver, which carries the mandrel with the package.
The winding machine can also be provided with a thread changing device and with a thread drawing-in device operating in conjunction with this thread changing device. The ends of a thread guide member of the thread changing device are carried by the ends of rotatable parallel carrier levers, with one of the carrier levers actuated by a servo-motor.
A known thread changing system of this type, disclosed in U.S. Pat. No. 4,136,834, has a thread changing device which includes a thread guide member, both ends of which are supported by carrier levers that swing about a common axis. One of the carrier levers is driven by a linear servo-motor. A disadvantage of the known thread changing device exists in that the driven end of the guide member is not vibration free. A further disadvantage exists with regard to the long length of the guide member (especially in the case of multi-package winding machines) in that the movements of the two ends of the guide member may not be synchronized. Further, the guide member includes a plurality of axially movable thread guides and a thread drawing-in device by which the axial movements of the thread guides are effected by means of a screw spindle driven by an electric motor. A disadvantage exists due to the high weight of the thread guide member and because the driving motor occupies considerable space and requires flexible electrical leads, which are susceptible to disturbances.
The invention involves the development of a thread changing system of the previously described type wherein the thread guide member is vibration free and its two ends move in synchronism.
The invention further involves producing a thread change system with a thread drawing-in apparatus which has low weight and the drive of which occupies only a small amount of space.